DB48X: HP48-like RPL implementation for DM42

[Paul Dale]

(08-16-2023 05:53 PM)c3d Wrote:  Short version: C47/WP43 uses their own floating-point code (derived from WP34 I believe), whereas DM42 and DB48X use the Intel decimal floating-point library.

Long version: the Intel library is IEEE-compliant, and takes a lot more space, notably due to relatively large tables used to accelerate various computations.

The C47/WP43 do indeed use the WP 34S as a base. That was based, in turn, on IBM's decNumber library which is also IEEE compliant and supports variable length numbers.

Intel's library does include a lot of lookup tables. It also uses binary floating point to get estimates which are refined to get a decimal results -- this will also add space since two libraries are being carried. It is very much a space for speed trade off.

One distinction between the C47/WP43 and the WP 34S is that the latter is targeting 16 digit accuracy whereas the former are targeting 34 digits. The extra digits will slow things down, although the amount varies depending on the function.


Pauli